Inserted cutter blade and mounting therefor



Oct. 25, 1938. F. P. MILLER INSERTED CUTTER BLADE AND MOUNTING THEREFORFiled May 27, 1957 m L II. K M m Patented Oct. 25, 1938 e UN TED STATESTHEREFOR J INSERTED CUTTER BLADE AND MOUNTING Frank P Miller, Meadville,Pa. Application May 27, 1937, Serial No. 145,148

, 13 Claims.

This invention relates to cutting tools, particularly to blades forinserted blade cuttersand to It is customary in the inserted bladecutter art to provide one or more blade receiving slots inthe supportingbody of the tool and to provide on at least one side face of each bladealseries of parallel serrations arranged. to interengage with acomplemental series of parallel serrations formed on some element'oiithesupporting body, such as a wall of the slot or on a face of a wedge orother blade locking element positioned in the slot; the serrationsafiording means for adjusting the blade in relation to the support andfor assisting in anchoring it against movement under the impulse offorces tending to dislodge the blade in service operation of the tool. a

.Prior to the advent of this invention and those described inmyaforementioned prior copending applications it has been universalpractice to employ corresponding or identical serrations on the bladeand the support element, utilizing the conventional V-shaped serrationsin which, when intermeshedQthe V-shaped grooves of one member areoccupied by the V-shaped serrations of the other with the apices of theserrations extending almost to the groove bottoms and with the angularwalls of the grooves and serrations being in full face contact. It isobvious that where irregularities and imperfections exist'in theserrations there will inevitably be incomplete meshing, a serious defectinthe seating of blades in high speed and heavy'duty cutters.

It is well known to those versed in the art that the formation {ofconventional V-shaped serrations instellite, and other unmachinablealloys which are highly desirable in the manuiacture Also, in the caseof serrated blades made from high speed steel and similar ferrous metalsit is very desirable to form the serrations by the grinding method afterhardening to..avoid the warpage and distortion that are inevitable fromthe high temperaturesgnecessary to the heat treatment or 5 hardeningprocess. The usual procedure is to form the serrations by hobbing orbroaching while the steel is in an annealed condition, but thesubsequent heat treatment warps and distorts the blade and leaves ascale on the serrations, thus destroying the accuracy and trueness ofthe serrated surface.

The manufacturing problems involved in the commercial production ofserrations by grinding in hard or hardened cutter blades have beensolved. by practice of the inventions disclosed in my aforementionedprior applications, wherein by a special grinding process alternateserrations are'omitted. I have found it desirable in some instances,such as in producing coarse serrations which run 16 or less tothe inch,not to omit serrations in .order to avoid the creation of too wide a gapbetween the meshed bearing surfaces. By providing a specially designedtooth or serration as herein disclosed it has been made possible togrind coarse serrations in hard tool blades without the use of :V-shapedgrinding wheels and without eliminating any serrations. 1

It is to be understood that theterm coarse as used herein refers toserrations of the number of 16 or less tothe lineal inch, this being astandard pitch. Other standard pitches are known to the'art as fineserrations, these being 32, 24 and 20-to the inch. At the present time,

however, the standard 16 pitch serration is perhaps more widely usedthan any other.

An object of the present invention is to provide a blade for insertedblade cutters having a serrated blade holder,- and the blade itselfserrated in a manner toengage the holder, with the blade serrationscontacting the holder serrations near their bases only, that is, nearthe bottoms of the intervening grooves between the holder serrations andwith the holder serrations disposed in the grooves between the bladeserrations in spaced relation to the groove bottoms and in spacedrelation to the groove walls adjacent to the groove bottoms.

An additional object is to provide a hard or hardened cutter bladeground with serrations or teeth that are spaced sufficiently to allow ofthe use of a grinding wheel having wide blunt grooving portions, therebyavoiding the need for frequent redressing of the grinding wheel, and atthe same time allowing heavier feeds and higher speeds, all of whichquickens production and decreases the cost of manufacture.

A further object is to provide an insertable cutter blade serrated tomesh with a serrated'blade holder element in bearing. contact with onlythe inner end or bottom wall areas of the holder element grooves betweenthe holder element serrations.

Other objects will be apparent from the description.

The presentdisclosure is illustrative of practical embodiments of theinvention, and it is to be understood that the structural detailsthereof may be varied as desired in any manner not inconsistent with thescope of the invention as claimed.

In the drawing- 4 Figure 1 is a fragmentary front elevation of a rotarycutter equipped with a blade in accordance with the invention, partsbeing shown in section.

Figure 2' is a fragmentary plan view of the cutter. r

Figure 3' is an enlarged fragmentary perspective detail of one form ofserrations on a cutter blade. I

Figure 4 is a perspective view of a blade as serrated in the form shownin Figure 3.

Figure 5 is a fragmentary sectional view illustrating the meshingengagement between a cutter blade and a serrated wall of the holderslot, the bladebeing serrated asshown in Figures 3 and 4. I

Figure- 6 is an enlarged fragmentary perspective detail of analternativeform of cutter blade serration. I

- Figure 7 is a sectional view similar to Figure 5 but illustrating themeshed engagement of blade and'holder with the blade serrated as inFigure 6.

Figure 8' is a fragmentary section illustrating the meshed engagementbetween a serrated cutter blade and a serrated-wedge element of theholderr Figure 9'is a fragmentary sectional view i1lu s-' trating theconventional meshing between a conventionally serrated blade and'holderwall.

As shownin Figures 1 and 2, a tool body, here shown as a rotary cutterhead I0, is provided with one or more slots ll: forthe reception ofblades l2, one wall of each slot being provided with a plurality ofparallel V-shaped serrations II of conventional design. The serrationsof the holder are closely grouped and coact with complemental serrationsit formed ona face of the blade, meshing therewith to assist in holdingth blade in adjusted position in its slot. a

The blade of any particular slot is anchore in place by a segmentalwedge 15 positioned in a receiving socket recess [6 opening at ohesideinto the sl'iSt 'II andghaveing an axially disposed internally threadedbore in which operates a lifting screw ll. The recess It has a side wallinclined toward-the adjacent blade. to impart a camming action to thecomplemental wedge member I! which is formed with a flat portion bearingagainst the adjacent face of the blade. The cylindrical form of thewedge over that portion which is within its socket permits the wedge toturn about its axis so that its flat portion enters into full bearingcontact against. the opposed flat face of the blade. By this arrangementthe blade is firmly locked against shifting movement under the influenceof stress arising in service.

' the meshing elements.

It has heretofore been customary in the art to employ the universallyused V-shaped type of serration on both blade and slot wall, therespec-' tive serrations being complemental and meshing as illustratedin Figure 9 in which the serrations 'll' of theblade 12' extend in fullface contact entirely into and substantially fill the V-shaped groovesbetween the serrations I! of the holder element il', "This arrangementis entirely unsuited to. the 'mounting of exceedingly hard blades for aspreviously stated, V-shaped serrations cannot be formed'in suchblades inany practical manner other than by grinding, and in grinding this typeof serrations the thin tapered edge grinding wheel-21s constantlysloughed off so that the serrations and grooves are improperly formed,preventing proper face contact between I have found that by providingthe cutter blade with grooves between the serrations having a bottom andbottom side wall clearance for the enholder element the serrations maybe ground in" the blade by grinding means having a blunt or obtusegroove forming portion that will retain its form over a very long periodof use as compared to the life of a tapered edge grinding element forproducing a V-shaped-groove. Also, in grooving to'provide such clearancethe contacting face area of the cutter blade serrations is reduced-"sothat in meshing, the apices of the holder serrations and an adjacentarea of their apex portions are not contactedv by the serrations of theblade.

The blades herein shown are serrated bythe forming process disclosedinmy copending application filedconcurrently' herewith and entitledMethod and apparatus for making cutter blades.

In the form illustrated in Figures 3, 4 and 5. the serrations ll of theblade I! have conventional V-shaped crests with sloping faces'itseparated by grooves l9 having rounded bottoms and parallel side walls20 which extend outwardly to merge with the sloping crest faces It inobtuse angles at points occupying a common -plane passed transverselythrough the serrations at substantially the midpoint between the apexand base of each. The rounded bottom of each groove I9 curves inwardlyof the blade body so.

that the resultant grooves provide ample housing clearance for theentrant apices of the holder element serrations H as shown best inFigure 5 when the blade is-seated in its holder slot with the serrationsmeshing.

In the embodiment illustrated particularly in Figures 6 and 7, the bladebody, here designated as H2 is identical with that of the blade l2except that the bottoms of the grooves m are flat and'the side walls I20extend outwardly at right "angles'therefrom in parallel relation tomerge at obtuse angles with thesloping faces I II of the V- shapedcrests of the serrations Ill at points occupying a common plane passedtransversely through the serrationsat substantially the mid pointbetween the apex and base of each. but

shaped bearing'crests and spaced apart by which meshiwith serrations241's the, opposed face of the madame, serrationsflbeing' of the ,formshowjnin eitherjiigure 3 or 6 as desired.

. I all embodimentsfof the invention the slop- "ing contactfacs of theblade serrations exist only over, their apex portions and do not extendto the groove bottom. in consequence, whena blade is positionedin itsholder the serrations mesh. with the serrations of the holder element,either slot wall or wedge, in bearing contact against only the bottomportions of the inclined walls which form the conventional V-shapedgrooves of the holder element serrations so that bearing contact isrestricted to surfaces where there is the least likelihood ofirregularities occurring in formation of the serrations, thus assuringmaximum etficiency in the meshing engagement of the blade and holderelement.

In the formation of the serrations as shown in Figure 6, the sharpcomers at the bottoms of the grooves will gradually become roundedas thecorners of the grinding wheel wear away, so that the angles of thecorners change in time to curved surfaces which approach in form thecurved groove bottoms of the embodiment shown in Figure 3. In eitherevent, the purpose of the invention will be'carried out successfully.

Having thus described the invention, what is claimed is:

1. A blade for inserted blade cutters, comprising a body having a faceportion thereof formed with a plurality of parallel serrations, saidserrations being spaced apart by grooves, and the serrations havingV-shaped crests providing sloping bearing faces merging with the sidesof the grooves at obtuse angles. 1

2. A blade for inserted blade cutters, comprising a body having a faceportion thereof formed with a plurality of parallel serrations, saidserrations being spaced apart by grooves, the serrations having V-shapedcrests providing sloping bearing faces merging with the sides of thegrooves at obtuse angles and being of a height substantially greaterthan the height of a conventional serration of the same pitch.

3. A blade for inserted blade cutters having conventionally serratedblade holder means, comprising a body having a face portion thereofformed with a plurality of serrations of the same pitch as theserrations of the holder means, said blade serrations having V-shapedcrests and being spaced 'apart by grooves having substantially parallelside walls merging with the sloping bearing faces of the crests atobtuse angles, the height of the blade serrations being substantiallygreater than the height of a conventional serration.

4. A blade for inserted blade cutters comprising a body having a faceportion thereof formed with a plurality of parallel serrations, saidserrations being spaced apart by grooves and having V-shaped crestsproviding sloping bearing faces merging with the sides of the grooves atobtuse angles, the height of said serrations being substantially greaterthan the height of a'conventional serration, whereby substantialportions of the entrant conventional serrations are housed in the bladegrooves in spaced relation to the walls thereof;

5. A blade for inserted blade cutters having conventionally serratedblade holder means, comprising a body having a face portion thereofformed with a plurality of parallel serrations of the same pitch as theserrations on the holder means with which the blade serrations areintended to mesh, said blade serrations having V- groovesof sufficientdepthand widthto' receive out of contact with the walls thereofsubstantial portions bf entrant ,nventiona'l' serrations. J

" blade cutters comprisportionthereof formed V with "a Tofserratio 'ns,said serrations beingspacedal art by grooves having sub- 4 parallelsidewalls, said serrations having' v sh'ap'ed 'cre's'ts' providingsloping bearing faces merging with the outer ends of the side walls ofthe grooves at obtuse angles, the apices of the crests of saidserrations and the bottoms of said grooves being disposed respectivelyin common planes spaced apart a distance greater than the height of aconventional serration.

7. A blade for inserted blade cutters, comprising a body having a faceportion thereof formed with a plurality of parallel serrations, saidserrations being spaced apart by grooves, said grooves having roundedbottoms and substantially parallel side walls extending outwardlytherefrom, and each serration having a V-shaped crest providingoppositely inclined sloping bearing faces merging into the groove wallsat obtuse angles, the angle of each crest being equal to the anglebetween the side walls of a conventional serration groove.

8. A blade for inserted blade cutters, comprising a body having a facethereof provided with a plurality of parallel serrations, saidserrations being spaced apart by grooves having parallel side walls andbottoms perpendicular thereto. and said serrations being formed withV-shaped crests providing sloping bearing faces.

9. A blade for inserted blade cutters, comprising a body having a facethereof provided with a plurality of parallel serrations, saidserrations being, spaced apart by grooves having parallel side walls andbottoms perpendicular thereto, said serrations being formed withV-shaped crests providingsloping bearing. faces, the apices of thecrests of said serrations and the bottoms of said grooves being disposedrespectively in common planes spaced apart a distance greater than theheight of a conventional serration.

10. In combination, a slotted blade holder having an element thereofprovided with conventional serrations, a cutter blade in the holderslot, a plurality of serrations in a face of the blade and in mesh withsaid holder element serrations, the blade serrations being V-shaped andengaging the bottom areas only of the serration grooves in the holderelement, said blade serrations having intervening grooves with parallelside wall portions extending inwardly in spaced relation sufficient toreceive and house the apex portions of the holder element serrations outof contact with the groove bottoms.

11. In combination, a slotted blade holder having an element thereofprovided with conventional serrations, a cutter blade in the holder slotand having in one face thereof a plurality .of serrations of the samepitch as the holder element serrations and meshed therewith, the crestsof the blade serrations being in bearing contact only with the bottomareas of the holder element grooves, and the apex portions of the holderelement serrations being housed in the blade serration grooves in spacedrelation from the groove bottoms and the sides of the grooves adjacentthe bottoms.

12. A blade for inserted blade cutters having blade holder meansprovided with conventional V-shaped serrations, comprising a body havinga face portion thereof formed with a plurality of parallel serrations o!the same pitch'as theiserrations on the holder means with which theblade serrations are intended to mesh, said blade serrations havingV-shaped bearingcrests and being spaced apart by grooves of sufllcientarea to house out of contact therewith substantial portions of entrantconventional V-shaped serrations.

13. A blade for inserted blade cutters having a 10 holder element formedwith conventional V- shaped crests.

shaped serrations, comprising a body provided with a plurality ofparallel serrations of the same pitch as the serrations on the'holderelement, said blade serrations having outer V-shaped crests providingoppositely inclined bearing faces and being spaced apart by grooveshaving rounded bottoms and side walls extending outwardly therefrom andmerging with said .V-

FRANK P. BHLLER; 10

